As the infrastructure of major cities and towns in the developed world age, the sewer systems weaken. Pipe degradation, system blockage, water infiltration, and sewer leakage are major problems that aging sewer systems experience. As these problems persist, the sewer system may eventually experience total failure and entire sections of the sewer system may collapse. As a result, sinkholes may form and sewers may back up into homes and places of business. One method of addressing this critical infrastructure problem is the use of pipe lining techniques to rehabilitate existing sewer systems.
Cured-in-place pipelining is one such technique that includes rehabilitating an existing sewer system by creating a new pipe within an existing pipe. A liner, impregnated with a resinous material capable of curing and hardening, is inverted or pulled into a damaged pipe. The liner is pressed toward the wall of the existing pipe, and the resinous material is allowed to cure and harden. The result is a replacement pipe having the older pipe or “host pipe” on the exterior. The cured-in-place pipe acts to alleviate the problems caused by structural defects and blockages in the existing sewer system.
Mainline sewer pipes are normally lined from manhole to manhole. In sewer systems where the main pipes have been rehabilitated with a cured-in-place pipe, unsealed connections at service and lateral pipe junctions (collectively referred to herein as “lateral pipes” or “lateral pipe lines”) create problems. An unsealed connection is generally a product of installing a pipe liner within the main pipe and over the lateral pipe junction, then using a cutting tool on the pipe liner at the connection to reinstate service to the lateral pipe. Current methods for cutting/reinstating service to lateral pipes are described for example in U.S. Pat. No. 7,131,791 (Whittaker et. al.), which is incorporated by reference.
Some problems related to unsealed connections are caused by shrinkage of the pipe liner and unsealed connections at service/lateral pipe junctions. Shrinkage of a pipe liner after installation presents a problem for the longevity and effectiveness of a sewer system, especially at lateral pipe junctions. Most resinous materials experience some shrinkage after installation within an existing pipe. An annulus between the host pipe and the pipe liner is created often due to this shrinkage of the resinous material. The amount of shrinkage by a pipe liner depends on the resin used, the thickness of the liner, properly cooling the liner under controlled inflation pressure, long-term creep when subjected to hydraulic loading, as well as several other factors. This shrinkage allows water and debris to enter into the sewer system and migrate between the host pipe and the pipe liner from the ground surrounding the pipes, allows sewage to escape into the ground surrounding the pipes, and allows roots from surrounding vegetation to enter the annulus between the host pipe and the pipe liner.
Therefore, a need in the art exists for a new apparatus and method for effectively repairing an opening in a pipe which may be a crack in a length of pipe or the junction between two buried pipes.